Halo-substituted phenylazoimidazoles are described at CA 72:111427a (Khim. Geterotsikl Soedin 916-22, 1969). Other substituted phenylazoimidazoles are shown in J. Chem. Soc., 115, 226 (1919) and in J. Chem. Soc., 117, 1426 (1920). None of the references cited disclose the use of the compounds to treat an animal.
U.S. Pat. No. 3,480,630 discloses the use of 2-arylhydrazino-imidazoline-(2) as a hypotensive in warm-blooded animals.